Hydrogen can serve as a fuel in combustion or electrochemical power-delivering systems, but the storage of hydrogen fuel at moderate pressures and close-to-ambient temperatures is a challenge. For vehicle applications it is necessary to carry sufficient hydrogen on-board for power plant operation over a suitable travel distance before refueling. This requires storing hydrogen in a compact and safe storage vessel from which hydrogen gas can be delivered on demand from an engine, fuel cell, or the like.
Liquefaction of hydrogen would provide a dense storage medium, but it requires very low temperatures that are not practically maintained in most vehicle applications. Progress has been made in temporarily fixing hydrogen in metal hydride compounds but hydrogen storage capacity is low and high temperatures are required for hydrogen release. There remains a need for ways and materials capable of temporarily storing hydrogen for delivery to a vehicle powering device.